Cooling apparatus



March 10, 1936. w, MCNULTY ET AL 2,033,845

COOLING APPARATUS Filed 001;. 20, 1933 2 Sheets-Sheet l INVENTORS JOHN W.M5NULTY m:

G 2 MJLLBRD H-NELSON.

WITNESSES:

March 10, 1936- J. w. McNULTY ET AL COOLING APPARATUS Filed Oct. 20, 1935 CONDENSER VACUUM INS.HG. w m

WITNESSES:

I00 STEHM PRESSURE LBS. FIBS.

2 SheetsSheet 2 F/&.3.

INVENTORS JOHN W. MENULTY AND MILLHRD H. NELSON.

l s: M

ATTORN EY Patented 10, 1933 Q COOLING. APPARATUS John W. McNultm, Ridley Park, and'Millard A.

Nelson, Prospect. Park, Pa., assignors to Westinghouse Electric & Manufacturing Company, .East Pittsburgh, Pa., a corporation of Pennsylvanla Application October 20, 1933, Serial No. 694,513

- 9 Claims. (01. 62-152) Our invention relates to ejectors and it hasfor an object to improve the performance thereof so as to minimize the consumption of. motive fluid. for example, steam.

Where ejector apparatus" is used for vacuum producing purposes, for example, with steam jet.

cooling or refrigeration, economy in steam consumption may be secured by careful attention to the steam flow requirements and by designing the nozzles for maximum efliciency for specific steam conditions and condenser vacuum. Greater steam flow is.required to start an ejector than to maintain it in operation. According- 15 ly, therefore, if greater steam nozzle capacity is provided'tosecure greater flow for starting and less steam nozzle capacity with less flow is-provided to maintain the ejector in operation, more economical performance may be secured. Since flow is a function of the pressure of steam sup- 2 ply, an ejector may be maintained in operation,

with improved economy because of the lowpressure of the supply, by steam supplied at such a pressure to nozzles of such a design that it is not self-starting. To secure the economical ad- 25 vantage of providing only the necessary flow .to

maintain the ejector in operation, we provide a set of running nozzles having such design and giving such flow aswill maintain operation. However, as the running nozzles, for the pressure'supplied, are not self-starting, we provide an tional or starting set of nozzles which are e ective, with the running nozzles, to start the ejector, the starting nozzles being stopped after stable operation of the ejector is secured.

It is to be understood, of course; that the set yrs of running nozzles would be self-starting if the pressure of steam supplied were increased to a suilicient point, but better performance is tov be had by maintaining the steam pressure at a value consistent with safely maintaining the ejector in operation after it isstarted. For example, a nozzle may have such a design, that, if isteamwere supplied to it at a pressure of 125 uniisper square inch or above, it would be "self-starting; and, after being started, it would be. maintained in operation until the pressure supply declined to the breaki'point, for example,

55 invention is to provide an ejector furnished with 100 pounds per square inch. Economy of con- 5 sumption may, therefore, be secured by supplying steam to a nozzle at a pressure slightly above the steam whose pressure is controlled in such a way operation do not provide suflicientflow for starting but wherein additional, or starting, nozzles are employed to be used, with the running nozzles, to start the ejector, the starting nozzles being stopped after stable operation of theejector is secured.

Assuming an ejector is arranged between an evaporator and a condenser, if the absolute pressure in the condenser rises, this represents an increase in the back pressure for the ejector. On the other hand, if the absolute pressure in the condenser declines, this represents a reduction in such back pressure. The compression ratio of the ejector is fixed within reasonable limits and the increase in condenser temperature and pressure has to be met by increase in .steam consumption in the ejector and vice assuring low steam consumption. When the pressure of steam is controlled in this Way, it is desirable that the apparatus be arranged for the operation already referred to, that is, the pressure shall not fall below a value-somewhat above the break" point of the nozzle, thereby entailing two sets of nozzles, a running set and. a starting set. Furthermore, with condenser temperature control, while the running jets might be selfstarting under certain conditions, under other conditions they -would not be; and, therefore, the combination of running and starting jets is advantageous in assuring starting under all conditions within the performance range-of the apparatus. It is desirable to maintain the evaporator within "reasonably narrow limits of temperature in order that refrigeration may be best effected; and, to this end; we provide a thermostat in the evaporator or tank which controls the operation of the ejector-upon a predetermined minimum temperature being attained in the tank or evaporator, the ejector is stopped at that point and upon a predetermined maximum temperature of the tank or evaporator, the ejector is started. Starting of theejector and maintenance' of the best pressure for operation of the latter with our two sets of jets entails control of the latter so that the ejector may be started termed the curve orline of Starting pressures.

and then maintained in operation. Hence, the thermostat associated with the tank or evaporator operates mechanism to render both sets of jets effective, the mechanismincluding suitable delay means, effective after a predetermined period, for cutting out the starting nozzles. Therefore, a further object of our invention is to provide apparatus having these advantageous features of construction and of operation.

These and other objects are eifected by our invention, as will be apparent from the following description and claims taken in accordance with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a side elevationof an ejector embodying our invention;

Fig. 2 shows as embodiment of our invention wherein the ejector is automatically controlled;

Fig. 3 shows a further embodiment wherein a multiplicity of ejectors with automatic control of one of them is employed; and,

Fig. 4 is a diagram illustrating an operating principle involved in our invention.

Referring now to the drawings more in detail, in Fig. 1, we show an ejector, at I0, for translating medium from a suitable source, for example, from the tank or evaporator, at I I, the translated medium being compressed and discharged against a suitable back pressure, for example, to that existing in the condenser, shown at l2. The ejector, at I0, is of conventional construction, the suction end being connected to the evaporator or tank, at H, and the discharge end communicating with the interior of the condenser, at l2. Our invention consists in the modified arrangement for supplying steam cand for controlling motivation of jets so as to secure most economical operation.

The rate of steam consumption during the starting period is higher than that required to maintain the ejector in operation after ,being started. Therefore, we provide two sets of jets or nozzles, a set of running jets or nozzles I4 and a set of starting jets or nozzles it, both sets being effective when the ejector is to be started and the starting set I5 being cut out after the ejector is started and is in normal operation. The reason why two sets of nozzles are employed to satisfy the above conditions is that the motive steam for the jets is supplied at such a pressure that most economical operation can be secured, the pressure being such that, for the design. and capacity of running nozzles required for normal operation, the flow of the latter nozzles is insuflicient to.ei'- feet starting and it is, therefore, necmsary to increase the flow at such time by starting nozzles.

If the characteristics of an ordinary jet are considered, it will be found that a considerable range exists between what might be termed the self-starting point and the break point. For

- example, it might be assumed that the nozzle set I 4 would have sufllcient flow to start the ejector if steam were supplied thereto at 125 lbs. per

square inch and that, after starting, the ejector would be maintained in operation by the nozzle set M until the pressure dropped to 100 lbs. per sq. in. This will be clear from a consideration of Fig. 4, wherein the line A represents the break" limit for a nozzle, that is, if the pressure of motive steam supplied to the nozzle falls below the line A for any condition, then the nozzle will cease to operate. The line B represents the limit below which the nozzle is not self-starting and above which it is self-starting, and may, therefore, be A whstanfial margin, therefore, occurs between the lines A and B where a nozzle is not self-starting but where it is able to maintain operation after being started. From the point of view of economy of steam consumption, the ejector apparatus is operated to the best advantage, if steam is supwith our invention, steam is supplied to the nozzles at a pressure somewhat above the break point, the steam consumption being more and more economical as the break point is approached; and to compensate for the inability of the nozzles or jets II to be self-starting, the additional nozzles or jets l5 are employed, the nozzles or jets l5 serving to assist the nozzles it during the starting period and being rendered inactive after the ejector is started and is in normal opertion. To this end, we show a steam line It having a pressure control valve IT for controlling the pressure of steam supplied to the header l8 and from the latter through the passages I9 and to the running and starting jets, the passages I3 and 20 having valves 2| and 22 arranged therein. To start the ejector, both valves 2| and 22 are opened; and, after the ejector is in stable operation, the valve 22 is closed. I

In Fig. 2, the apparatus shown in Fig. 1 is sub-- ject to automatic control. A thermostat 23 in the condenser, at l2, controls a pressure-reducing valve "a so as to supply steam from the main l6 to the branches l9 and 20 at the most economical operating pressure. The tank or evaporator, at H, is provided with a thermostat 25 which controls mechanism for stopping and starting theejector, such mechanism opening both valves 2 la and 22a to start the ejector and then closing the valve 22a. The valves 2 la and 220 are preferably self-closing, by springs MD and 22b. Assuming that a predetermined low temperature is attained the thermostat would initiate operation of the control mechanism to start the ejector, the valves 2laand 22a being opened to start andplace the ejector in stable operation, whereupon the starting valve 22a is closed. 7

The thermostat 25 operates in response to predetermined tank or evaporator temperature to open. the valves 2la. and 2": against the force of biasing means, for examplef springs 2|ib and 22b, and to a low'predetermined temperature so that the springs may close the valves. Also, the mechanism which opens the valves in response to the thermostat includes time-delay means providing for automatic closing of the starting valve 22a' after a sufilcient interval has elapsed for stable ejector operation to .be established. By way of example, I show the thermostat 25 including a bellows 26, which expands with rise in temperature and which contracts with decrease in temperature. Expansion of the bellows, incident to increase in evaporator temperature to a sufiicientextent, closes the contacts 21 to complete a circuit from one side 28 of the line 33 through the solenoids 3|, 32, and 33 of the relays 34 and 35 and the dash pot switch 36 back to the other side 31 of the line 30. Closure of the relays 34 and 35 places the solenoids 39 and 49 in circuit and the consequent energization of the latter results in opening of the valves 2 la and 22a against solenoid it so that the starting jet is not inter-'- rupted until after a' desired interval has elapsed subsequent to starting of the ejector, the fixed contacts 42 being elongated to permit of, relative travel of the movable contact 4211 due to cooperation of the solenoid 33 and the dash pot 4| during the desired interval of maintaining the starting ejector in operation. As. soon as the contacts, 42 and 42a open, the circuit for the starting jet solenoid 40 is broken and the spring 22b immediately closes the starting valve 22a,

thereby stopping the starting jets. Upongthe atevaporator irom the condenser, this being necessary where it is desired to prevent the ejector passage from functioning as an equalizer between the evaporator and the condenser; and the gate valve may be operated by any suitable means, manually-operated as shown or preferably automatically operated as hereinafter described in connection with Fig. 3..

The apparatus may incorporate means to prevent the automatic control mechanism from being effective to placethe ejector in operationunless a predetermined vacuum in the condenser has been reached. To this end, we show a vacuum gauge, at 42b, wherein the mercury column functions as a contact to open and close the local circuit' at '43, which operates the relay, at 44. The relay includes a movable contact 44a cooperating with fixed contacts 441) so that, when the contacts are closed, current may flow from the line side 28 through the contacts 21, when thelatter are closed, to the controLmechanism as hereinbefore pointed out; however, if the contacts 44a and 44b are open, the automatic control mechanism is isolated from the supply circuit 30 even though the contacts 21 are closed; Upon the attainment of a predetermined vacuum in the condenser H, the local circuit 43 is completed, and the solenoid winding 440 is energized so as to move the core'44d downwardly to bring about closure oi. the contacts 44a and 441) against the force of suitable biasing means such as the spring 44c. 1

In Fig. 3. we show a further embodiment of our invention wherein a plurality of ejectors is arranged between the evaporator or tank, at H, and the condenser, at I2, the electors at Ilia being of the type generally shown and described in Fig. 1 and the ejector lob being or the type shown and described in connection with Fig. 2. The ejectors Illa and Nb are-supplied with steam irom'the header [8 through a reducing or pressure controlled valve l'la controlled by a thermostatfijl, steam at header pressure is supplied to the running and starting jets of each of the ejectors a through the intermediary of control valves Hand 22 as already described. Preferably,'the non-automatic ejectors have different capacities so that any one or different combinations thereof with the automatic ejector may be arranged to suit the load demand. The ejector passages of theejectors Ma and lb are provided with stop valve 45a and 45b, respectively, the stop valve of an ineffective ejector being closed to prevent pressure equalization between the condenser and the evaporator. Assuming that a certain capacity of refrigeration is required, then one or more of the ejectors Illa are placed in operation in the manner as hereinbefore pointed out and the ejector I0!) is used in connection therewith to take care of variations in the selected base load. The ejector lllb, as pointed out in connection with Fig. 2, is subject to automatic control, that is, a thermostat 25 in the evaporator controls the operation of the valves Zla and no as well as the stop valve 45b. Upon the attainment of a predetermined low. temperature in the evaporator, the ejector Illb is cut out, the remaining ejector or ejectors Illa continuing in operation; and, as already pointed out, when the V ejector Hlb is cut out, both the valves-2|a and 22a are closed and the stop or gate valve 45b is closed in order to avoid aby-pass connection between the evaporator and the condenser. By way of example, we show the following means for effecting automatic control: the solenoid bellows 26 moves a switch arm 46, which engages either the contact 41, upon the attainment of a predetermined high evaporator temperature, or the contact 4130, upon the attainment of a predetermined low evaporator temperature. With engagement of the arm 46 with the contact 41, a

circuit will be completed from the side 28a of the line a through the relay solenoid 48, the dash pot solenoid 49, and the relay solenoid 50, to the return 5! going to the other side 31a of the line 30a. Energization of the solenoid 48 pulls up the core 48a to close the contacts 52, energization of the solenoid 49 pulls up the core 490 to open the moving contact 53 relative to the elongated contacts 53a after a suitable interval to provide for delayed cutting ofi of the starting jets, and

energization of the solenoid 50 raises the core .40

50a to close the contacts 55.

Closingoi' the contacts 55 completes a circuit from the line side 28a through the solenoid 59 to the return 5i, thereby providing for opening of the running jet valve Zia. The starting jet solenoid is energized at the same time, current therefor passing from the line side 2811, through thecontacts 52 and 53, to the solenoid 40, and from the latter to the return line 5| going to the other line side 31c. As before, the dash pct 54 associated with the core 49a assures' suflleient and the dash pot switch willresume the position shown in Fig. 3.

The gate valve b serves to close the' passage of the ejector lllb when the latter is not in operation, whereby such passage is prevented from equalizing pressures in the evaporator and in the condenser. Preferably, the gate valve is opera ated in timed relation with the control of the ejector. 'To this end, byway. of example, we show the gate valve opened and closed by the reversible electric motor, at 58, :having split field elements 59 and 60 having a common lead 6i going to the armature 62, the latter being connected by a lead 63 to the return 5| going to the line side'31a. Leads 64 and 65 are connected to the field elements 59 and 60, respectively, and it will be apparent that, if a circuit is completed through one lead, the motor will run in one direction, and, if the circuit is completed through the other lead, the motor will run in the other direction. Motion of the armature 62 is applied to the gate valve soas to open andclose the latter, the armature being shown as provided with a pinion 66 meshing with a rack 61 connected to the gate valve.

, The motor, M58, is provided with a conventional limit switch having contacts 68 and 69, one

of these contacts being closed incidentto opening of the other, that is, opening of contacts 66 to end the necessary motor travel to open the gate valve closes the contacts 69 so that when the lead 65 is later energized the motor will operate in the other direction to close the gate valve. With the contact 46 engaging the contact 41, the ejector 10b will be energized and thereafter the starting jet will be interrupted due to the time delay afforded by the dash-pot controlled contacts 53 and 53a. Incident to rendering the automatic ejector efiectivecurrent also passes from the line side'28a through the contact 68 and the lead 64 to the field element 55 to cause rotation of the motor 58 in such a direction as to open the gate valve b. If the arm 46 moves away from the contact 4'! and engages the contact 48c incident to attainment of a predetermined. low evaporator temperature, then a circuit will be completed from the line side 28a matic ejector lob in order to prevent the ejector passage from equalizing pressures in the evaporator and in the condenser, this result may be achieved more effectively by providing such sequences that the gate valve is completely closed before the supply of steam to the automatic ejector is cut off and the supply of steam to both the running and starting jets of the automatic ejector is established before the gate valve is opened. Also, I prefer to have the running and starting jets maintained in operation after the gate valve is opened so as to insure stable operation of the ejector before steam is cut oil! from the starting jets.

Referring to the sequence of the events accompa y starting of the ejector, we show a movable contact H connected to the core 49a and arranged to engage with the elongated contacts 12, engagement thereof taking place after a short distance of travel of the core, for example, the distance a.' This provides for a suflicient intervalto insure starting of the running and starting jets. Upon engagement of the contacts ll and 12, current is supplied from the line side 26a, through the contact 68, the lead 64, and the field element 59 to energize the motor, at 56, to open the gate valve, operation of the motor ceasing due to opening of the limit switch con-' tacts 68 and closing of the contacts 69 when the gate valve is fully open. We prefer that the starting jets shall not be stopped until after the gate valve 45b is open so that the ejector may be stabilized under working conditions, this sequence being easily provided for by making the contacts 53a sufliciently long and the dash pct 54 sufiiciently slow in action to provide for disengagement of the contacts 53 and 53a after the motor, at 58, has opened the gate valve, operation of the starting jets being continued until such time as the circuit including the contacts 53 and 53a is interrupted bythe opening of such con-- tacts.

When the automatic ejector lob is stopped, it is desirable to close the gate valve 45b before the steam supply to the running jets is interrupted. To this end, when the contact arm 46 engages the contact 480 to energize the motor, at 58, to

close the gate valve 45?), the latter will'start to close, but as the rack 61 has a contact I5 engaging a pair contacts 16 and 11, connected, respectively, to the solenoid 39 and to the line side 280, it will 'be seen that the solenoid 39 will continue to be energized to maintain the running jet in operation after the arm 46 moves away from the contact 41 and until the rack contact 15 disengages the pair contacts I6 and TI, disengagement of the latter being effected with closure of the gate valve.

As in Fig. 2, the arrangement shown in Fig. 3 is preferably provided with a vacuum responsive relay so that the automatic control for the automatic ejector cannot be operated unless a predetermined vacuum has been attained in the condenser, that is, the condenser i2 is provided with avacuum gauge 421) which completes the circuit 43 upon a predetermined high vacuum existing in the condenser l2. Completion of the circuit 43 operating the relay at 44 closes the contacts 44:: and 44b whereupon current may flow from the line side 26a through the contacts 46 and 41 and the contacts 44a and 44b-to the apparatus in the manner hereinbefore pointed out. In case the vacuum is impaired or is not sufliciently high, the circuit 43 will be interrupted and consequently the contacts 44a and 44b will be opened, whereby, irrespective of closure of the contacts 46 and 41, the automatic control mechanism circuits cannot be operated to motivate the automatic ejector.

While we have referred to running and starting jets, which is the'running jet and which is the starting jet may depend upon condenser temperature and pressure conditions and the relative capacities of the jets; Assuming that the capacity and steamdonsumption of the running jets is somewhat larger than that of the starting jets, with a suffi cient reduction in condenser temperature and pressure, as may be occasioned by reduced temperature of circulating water, it may be more economical to use the starting jets as the running jets, both sets of jets,-as before, being used to initiate operation of the ejector. Then again, under other circumstances, for example, with increase in steam pressure to a sufficient extent or with decrease in condenser absolute pressure "to a suflicient point, one set of nozzles may be adequate both for starting and running; however, as already pointed out, it is advantage ous to reduce the steam flow, as by stopping the starting nozzles, after the ejector is in stable operation. Also, where we refer to nozzles or set of nozzles; either starting or running, it is to be understood that one or more nozzles is intended, the number being a matter of design. I

The starting and running jet arrangement with control mechanism operating in respoee to evaporator temperature is disclosed and claimed in application of D. W. R. Morgan and J. W. Mc- Nulty Serial No. 694,512 filed concurrently herewith and asigned to Westinghouse-Electric 8: Manufacturing Company.

While we have shown our invention in three forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and we desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What we claim is:

1. In refrigeration'apparatus, an evaporator;

J a condenser; a booster ejector having its inlet end connected to the-evaporator and its discharge end connected to the condenser, said ejector including one or more running nozzles capable of maintaining operation after the ejector is started but incapable of starting the ejector and one or more starting nozzles, effective with the running nozzles, in starting the ejector; means for interrupting the supply of motive steam to the starting nozzles after'the ejector is started; and means for controlling the pressure of steam supplied to the nozzles in accordance with the condenser temperature conditions.

2. The combination, as claimed in claim 1, with means responsive to evaporator temperature conditions for placing the ejector in operation and for interrupting the operation thereof.

' responsive to evaporator temperature conditions,

3. In refrigerating apparatus, an evaporator; a condenser; an ejector provided with a diffuser having its inlet end connected'to the evaporator and its outlet end connected to the condenser; said ejector including running and starting steam jets; a main for supplying steam to the jets; means operating in accordance with the condenser temperature for maintaining steam pressure in the main dependent upon the condenser temperature; and means for controlling the supply of steam from said main to the running and starting jets and providing for the interruption of steam supply to the starting jets after I the ejector is .in operation.

4. In refrigerating apparatus, an evaporator, a

condenser, a plurality of ejectors including an automatic ejector for connecting the evaporator to the condenser, each of said ejectors including running and starting jets, means for maintaining a supply of steam under desired pressure, and

means for supplying steam from said supply to therunning and starting jets of the ejectors and providing for interruption of the supply to the starting jets after the ejectors are in stable operation, said last-named means including means for controlling the supply of steam to the automatic ejector.

5. In refrigerating apparatus, an evaporator; a condenser;..a plurality of ejectors connecting the evaporator to the condenser and including one or more non-automatic ejectors and an automatic ejector; each of said ejectors including running and starting jets; means providing a supply of steam under desired pressure; means for supplying steam from the supply-to the running and starting jets of each of the non-auto .matic ejectors to start the latter and providing for interruption of the supply to the starting jets after said ejector or ejectors are started; and means responsive to evaporator temperature conditions for supplying steam to the starting and running jets of the automatic ejector to start the latter, to interrupt the supply of steam to the starting jets after the ejector is in stable operation and to interrupt the supply of steam to the ejector.

6. In refrigerating apparatus, an evaporator; a condenser; one or more non-automatic ejectors and an automatic ejector connecting the evaporator and the condenser; each of said ejectors including running and starting jets; a header;

and the running and starting jet valves of the automatic ejector to start the latter followed by closure of the starting passage valve after the ejector is started and for closing all open valves incident to stopping the automatic ejector.

'7. The combination as claimed in claim 6' wherein a plurality of non-automatic ejectors of varying capacities are employed so that they may be selectively placed in operation to meet different demands.

8. In apparatus of the character described, a chamber, a condenser, an ejector connecting the chamber to the condenser, said ejector including nozzle means, a gate valve for opening and closing the ejector passage, means providing for the opening of the gate valve after the nozzle means is supplied with steam and providing for closure of the gate valve before the supply of steam to the nozzle means is interrupted, and means respon- -sive to pressure conditions existing in the condenser to prevent motivation of the ejector and opening of the gate valve until a predetermined high vacuum exists in the condenser.

9. In vapor jet refrigerating apparatus, the combination of evaporator means, a plurality of means to effect cooling by evaporating of liquid, said non-automatic ejectors being of varying capacities and being selectively operable to meet different cooling demands, and means responsive to evaporator temperature for controlling the operation of the automatic ejector.

JOHN W. McNUL'I'Y.

MIILARD A. NELSON.

non-automatic ejectors and an automatic ejector for withdrawing vapor from said evaporator 

